OBJECTIVESTo analyze the correlation between intervertebral disc-endplate degeneration and bony construction parameter and to explore its roles in adult degenerative scoliosis.

METHODSThe imaging data of 79 patients with adult degenerative scoliosis from March 2005 to March 2010 were retrospectively reviewed as the study group. The imaging data of 41 patients with adolescent idiopathic scoliosis were selected as the control group. The vertebral body and intervertebral height in both sides on frontal X-ray, and the facet joint orientation in both sides on CT scan were measured respectively. The average vertebral body height, average intervertebral disc height and average facet orientation were regarded as bony structural parameters. The quantitative grading methods were used in the intervertebral disc and endplate degeneration. The relationship of bony construction parameter and intervertebral disc-endplate degeneration, and the relationship of bony construction parameter and Cobb's angle of scoliosis were analyzed by comparing all bony construction parameters in both groups.

RESULTSAnalyzed by paired-t test, the intervertebral height, vertebral body height and facet joint orientation between convex and concave sides of the study group were of significant difference (t = 3.411, 2.623 and 2.085, P < 0.05). The intervertebral height between convex and concave sides of the control group were of significant difference (t = 3.276, P < 0.01), while the vertebral body height and the facet joint orientation were of no statistical significance (t = 1.572 and 1.493, P > 0.05). By linear correlation and regression analysis, the asymmetric degree of bony construction parameter showed good correlation with the score of intervertebral disc-endplate degeneration (-1 < r < 1, P < 0.05), which was positively correlated with Cobb's angle of scoliosis (0 < r < 1, P < 0.05). Linear regression existed between asymmetric degree of bony construction parameter and Cobb's angle (F = 427.342, P < 0.01). The regression function was obtained: Cobb's angle = -8.904+8.136 × IAD + 3.274 × VAD-0.713 × FAD (IAD: intervertebral asymmetry degree, VAD: vertebral asymmetry degree, FAD: facet joint asymmetry degree).

CONCLUSIONSThe asymmetric change of bony construction exists in adult degenerative scoliosis, which significantly correlated with intervertebral disc-endplate degeneration and Cobb's angle of scoliosis. The asymmetric bony construction parameter probably plays a biomechanical role in the progression of scoliosis, which maybe the reason for the asymmetric degeneration of intervertebral disc-endplate.